1. Field of the Invention
The present invention generally relates to the field of automatic faucets. More particularly, the present invention relates to a control arrangement for automatic faucets that interprets detailed information about the location and motion of objects to determine the intentions of a user, thereby providing an automatic faucet that is easier and more efficient to use.
2. Description of the Related Art
Automatic faucets have become popular for a variety of reasons. They save water, because water can be run only when needed. For example, with a conventional sink faucet, when a user washes their hands the user tends to turn on the water and let it run continuously, rather than turning the water on to wet their hands, turning it off to lather, then turning it back on to rinse. In public bathrooms the ability to shut off the water when the user has departed can both save water and help prevent vandalism.
One early version of an automatic faucet was simply a spring-controlled faucet, which returned to the “off” position either immediately, or shortly after, the handle was released. The former were unsatisfactory because a user could only wash one hand at a time, while the later proved to be mechanically unreliable.
A better solution was hands-free faucets. These faucets employed a proximity detector and an electric power source to activate water flow without the need for a handle. In addition to helping to conserve water and prevent vandalism, hands-free faucets also had additional advantages, some of which began to make them popular in homes, as well as public bathrooms. For example, there is no need to touch the faucet to activate it; with a conventional faucet, a user with dirty hands may need to wash the faucet after washing their hands. Non-contact operation is also more sanitary, especially in public facilities. Hands-free faucets also provide superior accessibility for the disabled, or for the elderly, or those who need assisted care.
Typically, these faucets use active infrared (“IR”) detectors in the form of photodiode pairs to detect the user's hands (or other objects positioned in the sink for washing). Pulses of IR light are emitted by one diode. When an object enters the detection zone, the other diode detects reflections of the emitted light off the object. Different designs use different locations on the spout for the photodiodes, including placing them at the head of the spout, farther down the spout near its base, or even at positions entirely separate from the spout.
Examples of hands-free faucets are given in U.S. Pat. No. 5,566,702 to Philippe, and U.S. Pat. No. 6,273,394 to Vincent, and U.S. Pat. No. 6,363,549 to Humpert, which are hereby incorporated in their entireties.
One shortcoming of typical automatic hands-free faucets is the potential for their activation by false detections. A stray object in the sink, such as a toppled bottle, or dishes left to dry, may trip the IR detectors and activate the water. Potentially, the faucet can become “stuck” on, leaving the water running indefinitely until a user returns and notices the running water, and clears the stray object. A number of control systems have been developed to attempt to combat this shortcoming, such as the one disclosed in U.S. Pat. No. 5,566,702 to Philippe.
This shortcoming is merely one example of the ways in which existing hands-free faucets imperfectly respond to the intentions of the user. Ideally, the natural and reflexive actions of the user in positioning objects under the spout of the faucet will activate water flow when it is desired, and at no other time.
Thus, what is needed is a control arrangement that can receive and interpret more detailed information about what the user is doing, and use that information to more accurately determine the intentions of the user. In particular, a control arrangement is needed that reduces or eliminates the potential false detections caused by stray objects, and which is therefore less prone to being stuck in an on state. A control arrangement is also needed that can better discriminate between objects left in the sink basin, such as dishes left to dry, and the hands of a user who is actively using the sink. A control arrangement is needed that can achieve these goals without requiring excessive power consumption, resulting in the need for frequent changing of batteries. The present invention is directed towards meeting these needs, among others.